A Scalable Small Array Design Method for Generating Multi-mode OAM Waves

The key to orbital angular momentum (OAM) communication lies in the multiplexing of multi-mode OAM vortex waves, which can be generated by multiple concentric uniform circular array (UCA). In this paper, a design method for small and scalable array for generating multi-mode vortex waves is proposed, and this array has regularity. The design concept is that the distance between adjacent UCAs is equal, the distance between adjacent elements in each UCA is equal, and the distance between adjacent elements in all UCAs is equal. The proposed array designed method has advantages such as regularity, scalability, and smaller volume. Compared with traditional concentric ring array antenna, simulation results show that the vortex waves generated by the designed array have higher mode isolation. The proposed array design method is beneficial for reducing mutual coupling between antenna elements and reducing the size of antenna array. Therefore, OAM beams with higher quality and ability to reuse more modes can be generated, which is of great significance for achieving multi-mode OAM multiplexing communication.